Wall-to-bed heat transfer in circulating fluidized beds

Fox, W. B.; Grewal, N.S.; Moen, Donald

doi:10.1016/s0735-1933(99)00035-4

Cited by 12 publications

(7 citation statements)

References 11 publications

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“…Due to the variation of these hydrodynamic characteristics between each of these regimes, heat transfer differs considerably among these regimes. For the bubbling regime, the data of Bearg et al (1950) was used and for the turbulent regime the data of Gupta and Nag (2002) was used while the data of (Fox et al 1999, Li et al 2004, and Reddy and Nag 1997 were used for the fast flow regime. Table (3) shows the operational ranges of experimental heat transfer studies used.…”

Section: Neural Network Design Training and Validationmentioning

confidence: 99%

Hybrid Modeling of Modified Mathematical Model for Gas Phase Olefine in Fluidized Bed Catalyst Reactors Using Artificial Neural Networks

Ibrehem¹

2009

Chemical Product and Process Modeling

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The complex flow patterns induced in fluidized bed catalytic reactors and the competing parameters affecting the mass and heat transfer characteristics makes the design of such reactors a challenging task to accomplish. The models of such a process rely heavily on predictive empirical correlations for mass and heat transfer coefficients. Unfortunately, published empirical based correlations have the common shortcoming of low-prediction efficiency compared with experimental data. In this work, an artificial neural network approach is used to capture the reactor characteristics in terms of heat and mass transfer based on published experimental data. The developed ANN-based heat and mass transfer coefficients relations were used in a conventional FCR model and simulated under industrial operating conditions. The hybrid model predictions of the melt-flow index and the emulsion temperature were compared to industrial measurements as well as published models. The predictive quality of the hybrid model was superior to other models. This modeling approach can be used as an alternative to conventional modeling methods.

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Section: Neural Network Design Training and Validationmentioning

confidence: 99%

Hybrid Modeling of Modified Mathematical Model for Gas Phase Olefine in Fluidized Bed Catalyst Reactors Using Artificial Neural Networks

Ibrehem¹

2009

Chemical Product and Process Modeling

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“…They proposed a model to describe the wall-to-bed heat transfer that is applicable over the entire range of possible local solid concentrations occurring in CFB systems. Heat transfer from the wall to the fast bed suspension was investigated for several materials such as sand, FCC, and steel by Fox et al [12]. They have conducted experiments on a single circular cross-section riser column operated with superficial velocity of air varying from 7.5 to 8.5 m/s at constant particle size of 150-µm.…”

Section: Introductionmentioning

confidence: 99%

“…References [12] and [13] are based on wall-to-bed heat transfer study while references [21] and [22] are based on bed-to wall heat transfer study. Thus, from the literature review, it is found that most of the heat transfer works on CFB were reported for the upper splash region of the riser and CFB hydrodynamics.…”

Section: Introductionmentioning

confidence: 99%

“…Extensive literature is available for heat transfer at the tubes suspended in the core of a CFB furnace [1][2][3][4][5][6][7]. However, such heat transfer data are not applicable for water walls at CFB furnace [8][9][10][11][12][13][14], as the flow pattern of the gas-solid mixture is quite different. Extensive literature [8][9][10][11][12][13][14] is available on bed-to-wall (membrane water wall) heat transfer characteristics for hot beds (bed temperature range: 800-1200 K) and wallto-bed heat transfer studies in cold CFB units (bed temperature less than 425 K).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, literature review reveals that very few articles are reported on heat transfer study related to lower and middle splash regions, such as those by Fox et al [12], Grulovic et al [13], Pagliuso et al [21], and Gungor [22]. References [12] and [13] are based on wall-to-bed heat transfer study while references [21] and [22] are based on bed-to wall heat transfer study. Thus, from the literature review, it is found that most of the heat transfer works on CFB were reported for the upper splash region of the riser and CFB hydrodynamics.…”

Section: Introductionmentioning

confidence: 99%

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Effect of scale-up of lower and middle splash region on heat transfer characteristics of circulating fluidized bed risers

Patil

Pandey

Mahanta

2010

Proceedings of the Institution of Mechanical Engineers, Part A:

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In the present work, a comparative study of steady-state wall-to-bed heat transfer was conducted along the lower and middle splash region located in the riser of height 2.85 m of three different circulating fluidized beds (CFBs) with bed cross-sections of 0.15 m × 0.15 m, 0.20 m × 0.20 m, and 0.25 m × 0.25 m. Experiments were conducted under similar operating conditions on above-mentioned three CFB set-ups using the same weight of sand per unit area of the distributor plate, non-dimensional superficial velocity (U * ), heat flux, and sand particle size. Further, experiments were conducted on all the three CFB set-ups for five different non-dimensional air velocities (U * = 5, 5.5, 6, 6.6, and 8) and two different weights of sand inventory per unit area of the distributor plate with average particle size of 460 µm. Bed temperature distributions across the lower and middle splash regions were measured and compared for the three bed cross-sections. Axial distributions of heat transfer coefficient along the height of lower and middle splash region of risers were evaluated and compared for the three bed cross-sections. The effect of superficial velocity, sand inventory, and bed cross-section on temperature and heat transfer coefficient was investigated. Based on the present study, correlations were developed for the bed Nusselt number as a function of various non-dimensional numbers for lower and middle splash regions of the riser. The non-dimensional area parameter (A * ) was found to be a significant number. Predictions of these correlations are in agreement (±16 per cent) with experimental data.

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Experimental and Computational Studies on Effects of Scale-Up of Riser on Heat Transfer Chatacterisitcs of Circulating Fluidized Bed

Patil

Mahanta

Pandey

2015

Transactions on Engineering Technologies

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Wall-to-bed heat transfer in circulating fluidized beds

Cited by 12 publications

References 11 publications

Hybrid Modeling of Modified Mathematical Model for Gas Phase Olefine in Fluidized Bed Catalyst Reactors Using Artificial Neural Networks

Hybrid Modeling of Modified Mathematical Model for Gas Phase Olefine in Fluidized Bed Catalyst Reactors Using Artificial Neural Networks

Effect of scale-up of lower and middle splash region on heat transfer characteristics of circulating fluidized bed risers

Experimental and Computational Studies on Effects of Scale-Up of Riser on Heat Transfer Chatacterisitcs of Circulating Fluidized Bed

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